In 2012, officials from the Pittsburgh History & Landmarks Foundation began drawing attention to the deteriorating arsenal structures.

One of the busiest facilities was the main lab, which employed 158 workers, the majority of whom were women engaged in the making of cartridges.

[6] The most commonly held view of the cause of the explosion was that the metal shoe of a horse had struck a spark which touched off loose powder in the roadway near the lab, which then traveled up onto the porch where it set off several barrels of gunpowder.

A coroner's jury held that the accident had been the result of the negligent conduct of Col. John Symington and his subordinates in allowing loose powder to accumulate on the roadway and elsewhere.

In the end Col. Symington was found innocent of any wrongdoing by the army, and the court concluded that "the cause of the explosion could not be satisfactorily ascertained...."

Col. Symington, in a letter to the Ordnance Department two days after the explosion, speculated that it had been caused "by the leaking out of powder when one of the barrels was being placed on the platform."

Alexander McBride, the Superintendent of the Lab, had repeatedly complained that the powder shipped by Dupont and Company was delivered in defective barrels with loose covers.

After the war, the Allegheny Arsenal served primarily as a storage facility for the Ordnance Department and Quartermaster Corps.

The arsenal's former main gate was demolished in 1947 to make more room for delivery trucks,[11] though it remained as a pile of rubble until the site was cleared for a new supermarket in 1961.

[12] All of the surviving buildings, along with several sections of stone wall surrounding the former arsenal, became contributing properties to the newly created Lawrenceville Historic District in 2019.